Large Patch: The Devastating Fall Patch Disease on Warm Season Turfgrasses

large patch disease on warm season turfgrass

We usually associate diseases with hot and humid weather of the summer, but diseases can occur throughout the year. One disease that is particularly devastating on warm-season grasses is called Large Patch. Brown Patch was the former name of this disease, and it is caused by the same fungi as Brown Patch, but it has been classified as a different lawn disease based on university research. Large Patch disease attacks Centipede, Zoysia and St. Augustine grasses. It can also affect Bermuda grass, but due to its aggressive growth habits, Bermuda often grows out of the disease.

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What Are the Symptoms of Large Patch Disease?

Symptoms of Large Patch lawn disease may be seen during periods of cool, wet weather in fall and spring. Many times, the symptoms of the disease are not evident until early spring when warm-season grasses begin to green-up in spring. Large Patch symptoms will look different depending on the turfgrass species and soil conditions.
These symptoms may show as thinned patches of light brown grass that are somewhat circular in shape from a few inches to several feet in diameter. Many times as the weather warms up, the center of the circular area will start to recover and leave behind a donut shaped ring.

What Is the Best Treatment for Large Patch Disease?

If your lawn had this disease last spring, treatment starts in the fall. There are several fungicides labelled to control Large Patch disease. Timing of the applications is important. Start the applications when soil temperatures reach about 70 degrees at a two inch depth. Depending on where you live, this could be early October to late November. The simplest way to check soil temperature is with an electronic meat thermometer. It is recommended that two applications are made in the fall about 30 days apart.

If you plan to make the applications yourself, be sure to read and follow all label directions. Spring-Green offices in warm-season areas offer Large Patch control applications. Call your local office to schedule this important preventative disease control treatment.